Improvement in electro-magnetic alarms



F. L. POPE.

Electromagnetic Alar ms. I v No.149,677. Patented ru14,1874.

Witnesses Inventor,

"PATENT. OFFICE.

FRANK L. POPE, OF ELIZABETH, NEW JERSEY.

IMPROVEMENT IN ELECTRO-MAGNETIC ALARMS.

Specification forming part of Letters Patent No. 149,677, dated April 14, 1874; application filed March 5, 1874.

ments in Electro-Magnetic Alarms, of which the following is a specification:

My invention consists in the employment of two electro-magnets acting alternately upon a single armature attached to a vibrating rod, the

latter being provided with two hammers, which are so arranged as to strike alternately upon a single bell or gong; also, in an improved circuit changing device, whereby the electric current is automatically switched or shunted from one magnet to the other, and vice versa, without being at any time interrupted; also, in making certain parts of the apparatus adjustable, by which means greater accuracy in the operation of the said apparatus is secured.

- The accompany in g drawing is afront elevation of the apparatus, a small portion of the vibrating rod being broken away to show the circuit-changer.

. A is a frame of wood or metal to which the different parts of the apparatus are secured. M and M are electro-magnets attached to the frame A, and provided with an armature, M, common to both, mounted upon a rod, D, which is suspended in the manner of a pendulum from the pivot m, and has another horizontal rod, D, secured to its lower extremity. Upon the ends of the rod D are screwed two hammers, Hand H, which. are placed just within the mouth of a concave or dish-shaped gong or bell, B, which is secured to the lower part of the frame A in such a position that when the rod D is caused to vibrate to and fro, the gong or bell B will be struck, and sounded alternately by the two hammers. The latter are capable of adjustment by being screwed backward or forward upon the rod D, and are secured in their position by means of check-nuts h and h. The circuitchanger F is pivoted at f, its upper portion being crutch-shaped, and provided with two adjustable set-screws, G and G, so arranged as to be struck alternately by a projection, d, upon the vibrating rod D. The lower end of the circuit-changer F carries a small metallic slide, 'K, the ends of which rest with slight pressure upon two plates, N and N, composed of some suitable insulating material, such as vulcanite, and provided with slips of metal L L, inlaid in such a manner that the whole forms a perfectly plane surface. One wire of the battery is attached to the binding-screw 0, from which a wire, 1, leads to the circuitchanger F. A wire, 2, leads from the insulated metallic slip L to the helices of the magnetM, and another wire, 3, connects the latter with the bindingscrew Z and the other wire leading to the battery. The opposite metallic slip L is connectedby the wire 4 to the other magnet M, from which the wire 5 leads to the binding-screw Z.

The operation of the apparatus is as follows Suppose an electric current to enter by the binding-screw C. It will traverse the wire 1, circuit-changer F, slide K, metallic slip L, wire 2, electro-magnet M, and wire 3, to the binding-screw Z, and thence back to the battery. The magnetM will then attract its armature m until the latter comes in contact with its poles, and the suspended rod D will participate in the movement. The momentum of the lower part of the rod D and its attachments, together with its elasticity, will cause the hammer H to strike the gong or bell B after the armature has come in contact with the poles of the magnet. At the same time the projection'd on the rod will strike against the point of the screw G, and reverse the position of the circuit-changer F, so as to move'the slide K out of contact withthe metal slip L, and into contact with the opposite slip L. This operation disconnects the circuit through M, and causes the-electric current, after reaching F, to traverse the wire 4:, magnet M, and wire 5, 'The magnet M now becomes active, and attracts the armature M to itself, and the gong or bell B is struck by the other hammer H, while at the same time the circuit-changer F is caused to return to its original position, and this operation is repeated as long as the electric current continues to flow.

The length of the slide Kis preferably made exactly equal to the distance between L and L, so that the circuit will not be broken during the movement of the slide fromone to the other. In order to facilitate the adjustment of the metallic slips L and L for this purpose, the plates N N are made movable, by means of the screws n a passing through elongated slots, as shown in the drawing. The travel of the slide K is adjusted by means of the setscrews G G.

From the above description it will be understood that each eleotro-magnet acts alternately upon the armature through the entire length of the stroke, its effect only ceasing after the armature is actually in contact with the poles of the magnet. Thus the movements of the armature and hammers are not impeded by any resistance whatever. On the contrary, during the initial portion of the stroke in each direction, when the magnetic attraction is least efl'ective, the motion is aided by the action of gravity.

I claim as my invention- 1. The electro-magnets M and M, (either or both,) the armature m, and vibrating rod D, in combination with the movable slide K and insulated metallic slips L L, substantially as herein specified.

2. The electro-magnets M and M, (either or both,) the armature m, and Vibrating rod D, in combination with the hammers H and H, (either or both,) and the bell or gong B, substantial] y as herein specified.

3. The rod D, provided with adjustable hammers H H, in combination with the bell or gong B, substantially as specified.

4. The adjustable metallic slips L L, in com bination with the movable slide K, arranged and operated substantially as specified.

5. The adjustable set-screws G G, so arranged as to regulate the travel of the slide K of the circuit-changer F, in combination with the vibrating rod D, substantially as specified.

FRANK 'L. POPE.

YVitnesses STEPHEN G. HENnnIoKsoN, JAMES M. ASHLEY. 

